Video: Line by Line Processing of Video on IT Hardware

If the tyranny of frame buffers is let to continue, line-latency I/O is rendered impossible without increasing frame-rate to 60fps or, preferably, beyond. In SDI, hardware was able to process video line-by-line. Now, with uncompressed SDI, is the same possible with IT hardware?

Kieran Kunhya from Open Broadcast Systems explains how he has been able to develop line-latency video I/O with SMPTE 2110, how he’s coupled that with low-latency AVC and HEVC encoding and the challenges his company has had to overcome.

The commercial drivers are fairly well known for reducing the latency. Firstly, for standard 1080i50, typically treated as 25fps, if you have a single frame buffer, you are treated to a 40ms delay. If you need multiple buffers for a workflow, this soon stacks up so whatever the latency of your codec – uncompressed or JPEG XS, for example – the latency will be far above it. In today’s covid world, companies are looking for cutting the latency so people can work remotely. This has only intensified the interest that was already there for the purposes of remote production (REMIs) in having low-latency feeds. In the Covid world, low latency allows full engagement in conversations which is vital for news anchors to conduct interviews as well as they would in person.

IP, itself, has come into its own during recent times where there has been no-one around to move an SDI cable, being able to log in and scale up, or down, SMPTE ST 2110 infrastructure remotely is a major benefit. IT equipment has been shown to be fairly resilient to supply chain disruption during the pandemic, says Kieran, due to the industry being larger and being used to scaling up.

Kieran’s approach to receiving ST 2110 deals in chunks of 5 to 10 lines. This gives you time to process the last few lines whilst you are waiting for the next to arrive. This processing can be de-encapsulation, processing the pixel values to translate to another format or to modify the values to key on graphics.

As the world is focussed on delivering in and out of unusual and residential places, low-bitrate is the name of the game. So Kieran looks at low-latency HEVC/AVC encoding as part of an example workflow which takes in ST 2110 video at the broadcaster and encodes to MPEG to deliver to the home. In the home, the video is likely to be decoded natively on a computer, but Kieran shows an SDI card which can be used to deliver in traditional baseband if necessary.

Kieran talks about the dos and don’ts of encoding and decoding with AVC and HEVC with low latency targetting an end-to-end budget of 100ms. The name of the game is to avoid waiting for whole frames, so refreshing the screen with I-frame information in small slices, is one way of keeping the decoder supplied with fresh information without having to take the full-frame hit of 40ms (for 1080i50). Audio is best sent uncompressed to ensure its latency is lower than that of the video.

Decoding requires carefully handling the slice boundaries, ensuring deblocking i used so there are no artefacts seen. Compressed video is often not PTP locked which does mean that delivery into most ST 2110 infrastructures requires frame synchronising and resampling audio.

Kieran foresees increasing use of 2110 to MPEG Transport Stream back to 2110 workflows during the pandemic and finishes by discussing the tradeoffs in delivering during Covid.

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Kieran Kunhya Kieran Kunhya
CEO & Founder, Open Broadcast Systems

Video: IP Media Networks for Live Production

Building and controlling a network for SMPTE ST 2110 go hand in hand when it comes to planning an installation. As ST 2110 delivers all media essences separately, networks can easily end up carrying tens of thousands of flows emphasising the need for efficient network design and having a full understanding of the paths your media are using.

This video is co-presented by Nevion and Arista and starts by observing that the traditional difference between a LAN and WAN is being eroded leading as WANs get faster and better, we find that we can now deliver multi-location broadcast facilities which act similarly to if everything was co-located. Moreover, introduces Martin Walbum Media Function virtualisation which is enabled by network-connected equipment allowing for shared processing and shared control. For instance, it’s now possible to house all equipment in a datacentre and allow this to be used remotely maximising the utilisation of the equipment allowing a broadcaster to maximise the value of its purchases and minimise costs.

Arista’s Gerard Phillips takes a look at SDI systems to understand how we expect IP systems to behave and what we expect them to do. The system needs to deliver high throughput, instantaneous switching with low latency and no tolerance for failure. In order to do this, not only do we need to get the right software but to deliver the resilience we need, the network needs the correct architecture. Gerard takes us through the different options starting with a typical, flat, layer 2 networks and working up to leaf and spine along with a treatment of red, blue and purple networks.

Gerard recently did a deep dive on network design for live production for the IET. Take a look for much more detail on how to architect a network for uncompressed media.

Martin then looks at the need for orchestration. Broadcasters expect to deliver systems with, preferably, no downtime. As such, we’ve seen that network elements are typically duplicated as is the traffic which is delivered over two paths and SMPTE ST 2022-7. If you want to take something out of use for planned maintenance, it’s best to do that in a planned, ordered, way meaning you migrate flows away from it until it’s no longer in-circuit. Software-Defined Networks (SDNs), do exactly that. Martin walks us through the pros and cons of managing your network with IGMP and SDN. Gerard’s previous talk also looks at this in detail.

The video finishes with a look at which Arista switches can be used for media and a look at how Arista and Nevion implemented an ST 2110 network at Swiss broadcaster, tpc. This case study is presented in longer form in this video from the IP Showcase.

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Gerard Phillips Gerard Phillips
Systems Engineer,
Martin Walbum Martin Walbum
Senior Vice President of Solution Strategy,

Video: HTTP over QUIC is the next generation

There’s a lot to like about HTTP/3 from encryption as standard, faster set-up time, better compression and promises better throughput by removing head-of-line blocking. A new protocol making its way through the IETF and based on QUIC, this could have a real impact on anyone involved in streaming.

wolfSSL’s Daniel Stenberg and cURL maintainer, talks to us about HTTP/3 but starts at the beginning with HTTP 1 and 1/1. He outlines some of the issues we had in 1997 such as head-of-line blocking and ephemeral TCP connections. Zooming forward to 2005, HTTP/2 comes on the scene with a single HTTP connection, thus removing the significant overhead of ephemeral TCP connections. HTTP/2 went with a ‘streamed’ connection and could have multiple such streams but one thing that wasn’t solved was head-of-line blocking.

Before moving beyond HTTP/2, Daniel describes the problems that have set in due to ‘ossification’, that is to say that the routers that time forgot which are still on very old, and often buggy TCP implementations. Innovating is very difficult if replacing the TCP within even a subset of boxes would mean I wasn’t able to send my website globally.

Addressing this ‘ossification’ issue, QUIC has stepped in. Developed on UDP instead of TCP QUIC solves a number of problems. First off, moving from TCP to UDP allows the protocol to live in userspace making it easier to update. Working on UDP instead of TCP means that the protocol regains control of the retransmissions allowing for something more efficient than TCP’s strict acknowledgement rules.

So QUIC becomes the transport layer of HTTP/3. Freeing ourselves from TCP, Daniel explains, allows us to remove the TCP head-of-line blocking problem. HTTP/3 on QUIC brings with it faster handshakes and a connection ID. This connection ID allows you to change IP addresses and still maintain your connection which is a significant improvement on what has gone before. Daniel continues by explaining more benefits of QUICK and HTTP/3 such as its encryption and the ability to have multiple streams.

Daniel finishes up outlining eight challenges for HTTP/3. These include the fact that up to 7% of QUICK attempts fail, dealing with ‘fall back’ algorithms, UDP having seen historically low usage and are less optimised as well as the downsides of userland protocol stacks being that it’s harder to get a standard.

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Download the presentation

Daniel Stenberg Daniel Stenberg
curl master, wolfSSL
main author,

Video: Is IP Really Better than SDI?

Is SDI so bad? With the industry as a whole avidly discussing and developing IP technology, all the talk of the benefits of IP can seem like a dismissal of SDI. SDI served the broadcast industry very well for decades, so what’s suddenly so wrong with it? Of course, SDI still has a place and even some benefits over IP. Whilst IP is definitely a great technology to take the industry forward, there’s nothing wrong with using SDI in the right place.

Ed Calverley from Q3Media takes an honest look at the pros and cons of SDI. Not afraid to explain where SDI fits better than IP, this is a very valuable video for anyone who has to choose technology for a small or medium project. Whilst many large projects, nowadays, are best done in IP, Ed looks at why that is and, perhaps more importantly, what’s tricky about making it work, highlighting the differences doing the same project in SDI.

This video is the next in IET Media’s series of educational videos and follows on nicely from Gerard Phillips’ talk on Network Design for uncompressed media. Here, Ed recaps on the reasons SDI has been so successful and universally accepted in the broadcast industry as well as looking at SDI routing. This is essential to understand the differences when we move to IP in terms of benefits and compromises.

SDI is a unidirectional technology, something which makes it pleasantly simple, but at scale makes life difficult in terms of cabling. Not only is it unidirectional, but it can only really carry one video at a time. Before IP, this didn’t seem to be much of a restriction, but as densities have increased, cabling was often one limiting factor on the size of equipment – not unlike the reason 3.5mm audio jacks have started to disappear from some phones. Moreover, anyone who’s had to plan an expansion of an SDI router, adding a second one, has come across the vast complexity of doing so. Physically it can be very challenging, it will involve using tie-lines which come with a whole management overhead in and of themselves as well as taking up much valuable I/O which could have been used for new inputs and outputs, but are required for tying the routers together. Ed uses a number of animations to show how IP significantly improves media routing,

In the second part of the video, we start to look at the pros and cons of key topics including latency, routing behaviour, virtual routing, bandwidth management, UHD and PTP. With all this said, Ed concludes that IP is definitely the future for the industry, but on a project-by-project basis, we shouldn’t dismiss the advantages that do exist of SDI as it could well be the right option.

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Ed Ed Calverley
Trainer & Consultant
Russell Trafford-Jones Moderator: Russell Trafford-Jones
Exec Member, IET Media Technical Network
Editor, The Broadcast Knowledge
Manager, Services & Support, Techex